|
Serotype
A serotype or serovar is a distinct variation within a species of bacteria or virus or among immune cells of different individuals. These microorganisms, viruses, or cells are classified together based on their surface antigens, allowing the epidemiologic classification of organisms to the subspecies level. A group of serovars with common antigens is called a serogroup or sometimes ''serocomplex''. Serotyping often plays an essential role in determining species and subspecies. The ''Salmonella'' genus of bacteria, for example, has been determined to have over 2600 serotypes. ''Vibrio cholerae'', the species of bacteria that causes cholera, has over 200 serotypes, based on cell antigens. Only two of them have been observed to produce the potent enterotoxin that results in cholera: O1 and O139. Serotypes were discovered by the American microbiologist Rebecca Lancefield in 1933. Role in organ transplantation The immune system is capable of discerning a cell as being 'self' or 'n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Serotypes – Antibody Versus Antigen
A serotype or serovar is a distinct variation within a species of bacteria or virus or among immune cells of different individuals. These microorganisms, viruses, or cells are classified together based on their surface antigens, allowing the epidemiologic classification of organisms to the subspecies level. A group of serovars with common antigens is called a serogroup or sometimes ''serocomplex''. Serotyping often plays an essential role in determining species and subspecies. The ''Salmonella'' genus of bacteria, for example, has been determined to have over 2600 serotypes. ''Vibrio cholerae'', the species of bacteria that causes cholera, has over 200 serotypes, based on cell antigens. Only two of them have been observed to produce the potent enterotoxin that results in cholera: O1 and O139. Serotypes were discovered by the American microbiologist Rebecca Lancefield in 1933. Role in organ transplantation The immune system is capable of discerning a cell as being 'self' or 'n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Salmonella
''Salmonella'' is a genus of rod-shaped (bacillus) Gram-negative bacteria of the family Enterobacteriaceae. The two species of ''Salmonella'' are ''Salmonella enterica'' and ''Salmonella bongori''. ''S. enterica'' is the type species and is further divided into six subspecies that include over 2,600 serotypes. ''Salmonella'' was named after Daniel Elmer Salmon (1850–1914), an American veterinary surgeon. ''Salmonella'' species are non-spore-forming, predominantly motile enterobacteria with cell diameters between about 0.7 and 1.5 μm, lengths from 2 to 5 μm, and peritrichous flagella (all around the cell body, allowing them to move). They are chemotrophs, obtaining their energy from oxidation and reduction reactions, using organic sources. They are also facultative anaerobes, capable of generating ATP with oxygen ("aerobically") when it is available, or using other electron acceptors or fermentation ("anaerobically") when oxygen is not available. ''Salmonella'' spe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Human Leukocyte Antigen
The human leukocyte antigen (HLA) system or complex is a complex of genes on chromosome 6 in humans which encode cell-surface proteins responsible for the regulation of the immune system. The HLA system is also known as the human version of the major histocompatibility complex (MHC) found in many animals. Mutations in HLA genes may be linked to autoimmune disease such as type I diabetes, and celiac disease. The HLA gene complex resides on a 3 Mbp stretch within chromosome 6, p-arm at 21.3. HLA genes are highly polymorphic, which means that they have many different alleles, allowing them to fine-tune the adaptive immune system. The proteins encoded by certain genes are also known as ''antigens'', as a result of their historic discovery as factors in organ transplants. HLAs corresponding to MHC class I ( A, B, and C), all of which are the HLA Class1 group, present peptides from inside the cell. For example, if the cell is infected by a virus, the HLA system brings fragme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HLA-DR
HLA-DR is an MHC class II cell surface receptor encoded by the human leukocyte antigen complex on chromosome 6 region 6p21.31. The complex of HLA-DR (Human Leukocyte Antigen – DR isotype) and peptide, generally between 9 and 30 amino acids in length, constitutes a ligand for the T-cell receptor (TCR). HLA (human leukocyte antigens) were originally defined as cell surface antigens that mediate graft-versus-host disease. Identification of these antigens has led to greater success and longevity in organ transplant. Antigens most responsible for graft loss are HLA-DR (first six months), HLA-B (first two years), and HLA-A (long-term survival). Good matching of these antigens between host and donor is most critical for achieving graft survival. HLA-DR is also involved in several autoimmune conditions, disease susceptibility and disease resistance. It is also closely linked to HLA-DQ and this linkage often makes it difficult to resolve the more causative factor in disease. HLA-DR mol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HLA-DQ
HLA-DQ (DQ) is a cell surface receptor protein found on antigen-presenting cells. It is an αβ heterodimer of type MHC class II. The α and β chains are encoded by two loci, HLA-DQA1 and HLA-DQB1, that are adjacent to each other on chromosome band 6p21.3. Both α-chain and β-chain vary greatly. A person often produces two α-chain and two β-chain variants and thus 4 isoforms of DQ. The DQ loci are in close genetic linkage to HLA-DR, and less closely linked to HLA-DP, HLA-A, HLA-B and HLA-C. Different isoforms of DQ can bind to and present different antigens to T-cells. In this process T-cells are stimulated to grow and can signal B-cells to produce antibodies. DQ functions in recognizing and presenting foreign antigens (proteins derived from potential pathogens). But DQ is also involved in recognizing common self-antigens and presenting those antigens to the immune system in order to develop tolerance from a very young age. When tolerance to self proteins is lost, DQ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HLA-B
HLA-B (major histocompatibility complex, class I, B) is a human gene that provides instructions for making a protein that plays a critical role in the immune system. HLA-B is part of a family of genes called the human leukocyte antigen (HLA) complex. The HLA complex helps the immune system distinguish the body's own proteins from proteins made by foreign invaders such as viruses and bacteria. HLA is the human version of the major histocompatibility complex (MHC), a gene family that occurs in many species. Genes in this complex are separated into three basic groups: class I, class II, and class III. In humans, the HLA-B gene and two related genes, HLA-A and HLA-C, are the major genes in MHC class I. MHC class I genes provide instructions for making proteins that are present on the surface of almost all cells. On the cell surface, these proteins are bound to protein fragments (peptides) that have been exported from within the cell. MHC class I proteins display these peptides to t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HLA-A
HLA-A is a group of human leukocyte antigens (HLA) that are encoded by the HLA-A locus, which is located at human chromosome 6p21.3. HLA is a major histocompatibility complex (MHC) antigen specific to humans. HLA-A is one of three major types of human MHC class I transmembrane proteins. The others are HLA-B and HLA-C. The protein is a heterodimer, and is composed of a heavy α chain and smaller β chain. The α chain is encoded by a variant HLA-A gene, and the β chain (β2-microglobulin) is an invariant β2 microglobulin molecule. The β2 microglobulin protein is encoded by the B2M gene, which is located at chromosome 15q21.1 in humans. MHC Class I molecules such as HLA-A are part of a process that presents short polypeptides to the immune system. These polypeptides are typically 7-11 amino acids in length and originate from proteins being expressed by the cell. There are two classes of polypeptide that can be presented by an HLA protein: those that are supposed to be expressed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virus
A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Since Dmitri Ivanovsky's 1892 article describing a non-bacterial pathogen infecting tobacco plants and the discovery of the tobacco mosaic virus by Martinus Beijerinck in 1898,Dimmock p. 4 more than 9,000 virus species have been described in detail of the millions of types of viruses in the environment. Viruses are found in almost every ecosystem on Earth and are the most numerous type of biological entity. The study of viruses is known as virology, a subspeciality of microbiology. When infected, a host cell is often forced to rapidly produce thousands of copies of the original virus. When not inside an infected cell or in the process of infecting a cell, viruses exist in the form of independent particles, or ''virions'', consisting of (i) the genetic material, i. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hemagglutination
Hemagglutination, or haemagglutination, is a specific form of agglutination that involves red blood cells (RBCs). It has two common uses in the laboratory: blood typing and the quantification of virus dilutions in a haemagglutination assay. Blood typing Blood type can be determined by using antibodies that bind to the A or B blood group antigens in a sample of blood. For example, if antibodies that bind the A blood group are added and agglutination occurs, the blood is either type A or type AB. To determine between type A or type AB, antibodies that bind the B group are added and if agglutination does not occur, the blood is type A. If agglutination does not occur with either antibodies that bind to type A or type B antigens, then neither antigen is present on the blood cells, which means the blood is type O. In blood grouping, the patient's serum is tested against RBCs of known blood groups and also the patient's RBCs are tested against known serum types. In this way the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Salmonella Bongori
''Salmonella bongori'' is a pathogenic bacterium belonging to the genus ''Salmonella'', and was earlier known as ''Salmonella'' subspecies V or '' S. enterica'' subsp. ''bongori'' or ''S. choleraesuis'' subsp. ''bongori''. It is a Gram-negative, rod-shaped bacterium (bacillus), which causes a gastrointestinal disease called salmonellosis, characterized by cramping and diarrhoea. It is typically considered a microbe of cold-blooded animals, unlike other members of the genus, and is most frequently associated with reptiles. It was discovered in 1966 from a lizard in the city of Bongor, Chad, from which the specific name ''bongori'' was derived. After decades of controversy in ''Salmonella'' nomenclature, it gained the species status in 2005. Pathogenicity and epidemiology ''S. bongori'' is classically regarded as the ''Salmonella'' of lizards. However, discrete investigations contradict the notion of strict host-specificity, as reports emerged of occurrence in dogs and bir ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lipopolysaccharide
Lipopolysaccharides (LPS) are large molecules consisting of a lipid and a polysaccharide that are bacterial toxins. They are composed of an O-antigen, an outer core, and an inner core all joined by a covalent bond, and are found in the outer membrane of Gram-negative bacteria. Today, the term ''endotoxin'' is often used synonymously with LPS, although there are a few endotoxins (in the original sense of toxins that are inside the bacterial cell that are released when the cell disintegrates) that are not related to LPS, such as the so-called delta endotoxin proteins produced by '' Bacillus thuringiensis''. Lipopolysaccharides can have substantial impacts on human health, primarily through interactions with the immune system. LPS is a potent activator of the immune system and pyrogen (agent that causes fever). In severe cases, LPS can play a role in causing septic shock. In lower levels and over a longer time period, there is evidence LPS may play an important and harmful role ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antigens
In immunology, an antigen (Ag) is a molecule or molecular structure or any foreign particulate matter or a pollen grain that can bind to a specific antibody or T-cell receptor. The presence of antigens in the body may trigger an immune response. The term ''antigen'' originally referred to a substance that is an antibody generator. Antigens can be proteins, peptides (amino acid chains), polysaccharides (chains of monosaccharides/simple sugars), lipids, or nucleic acids. Antigens are recognized by antigen receptors, including antibodies and T-cell receptors. Diverse antigen receptors are made by cells of the immune system so that each cell has a specificity for a single antigen. Upon exposure to an antigen, only the lymphocytes that recognize that antigen are activated and expanded, a process known as clonal selection. In most cases, an antibody can only react to and bind one specific antigen; in some instances, however, antibodies may cross-react and bind more than one antigen. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.jpg "Click for more on -> Salmonella")
